I don't know everything he does that takes that much time. I did ask him to pass some of his workload off to me, but he wants to be in control of every little detail. He won't add another crew because the sales people aren't bringing in enough to keep 2 crews working regularly.What exactly does your boss do 15 hours a day, 7 days a week? Are you capable of doing what he does? he is likely working that much to escape other life problems or needs organizational help Because he can’t do what needs doing in a reasonable time.
As an owner I felt my best course was to provide opportunities and reward performance. among Things I valued highly among people was initiative, it is one of the few things you can’t teach.
if he is asking you what you want to do, tell him you want to make his life easier and make both of you more money. Tell him what specifics of his job you can do now and what part you can do with more training. sell the benefit of how he can better spend his time.
another strategy would be to suggest adding another crew, you taking the supervisor role in the new crew until they are trained and a supervisor trained at which point you would repeat the cycle.
the longer you sit at home the worse this is going to get IMHO. Make something happen.